Emergency service is often available to a caller by dialing an emergency number, which may be some abbreviated string of digits, such as 9-1-1. When an emergency number is dialed by a wireline phone, a switching office in the telephone network e.g., public switching telephone network (PSTN), maps the emergency number to the route of a local public safety answering point (PSAP) serving the community in which the phone is located, and subsequently routes the call to the local PSAP through the telephone network using the mapped route.
In a larger community, there may be more than one local PSAP serving that community. When there are more than one local PSAP, the switching office must select a particular local PSAP to which to route the emergency call. The selected PSAP would typically be the local PSAP serving an area from which the emergency call originated. This manner of selecting and routing an emergency call to a particular local PSAP is part of a service known as Enhanced 9-1-1 (E911). E911 is often implemented in an entity referred to as an Emergency Services Network (EmSN). E911 utilizes a database which associates directory numbers (DN) for each phone in the community to the identity of the PSAP assigned to serve or answer emergency calls from phones within that community. When an emergency call is initiated, a calling party number (CgPN) associated with the caller, i.e., phone from which the call originated, is signaled with the emergency call. The CgPN indicates a DN associated with the phone and is used to select the PSAP to answer the call from that phone. The call is subsequently routed through the telephone network and EmSN to the PSAP.
Fraud prevention may be implemented to prevent fraudulent emergency calls from wasting valuable resources used in response to legitimate emergency calls. Fraud prevention may include one or more techniques for identifying possible fraudulent emergency calls. One such technique involves determining an emergency call may be fraudulent if multiple emergency calls were originated from a same phone over a short time interval. This technique, however, was originally designed to identify possible fraudulent emergency calls from wireline phones, not wireless phones. The main difference between wireline phones and wireless phones is that wireline phones have fixed locations and wireless phones do not have fixed locations. For purposes of this application, the term wireless phones include mobile terminals and not cordless phones. This difference is a significant factor in identifying possible fraudulent emergency calls, as will be explained below.
As mentioned earlier, a PSAP serves a particular area. An emergency call from a phone within a particular area will only be routed to the PSAP associated with that area. Since a wireline phone has a fixed location, an emergency call from the wireline phone will only be routed to its associated PSAP, i.e., the PSAP serving the area in which the wireline phone is located. Due to this one-to-one correspondence between wireline phones and PSAPs, emergency calls from a particular wireline phone will only be received by the PSAP serving the area in which that wireline phone is located and recorded at an emergency call register (ECR) associated with that PSAP (hereinafter referred to as “PSAP-ECR”).
By contrast, a wireless phone does not have a fixed location. There is no one-to-one relationship between wireless phones and PSAPs. When an emergency call is initiated by a wireless phone, the call is initially received by a serving mobile switching center (MSC). The MSC causes the call to be recorded at an ECR associated with the serving MSC (hereinafter referred to as “serving system ECR” or “SS-ECR”) and at a PSAP-ECR associated with a PSAP serving the MSC (in the same manner which a PSAP serves a community or an area within a community). Note that there is a one-to-many relationship between PSAPs and MSCs, i.e., one PSAP may serve multiple MSCs. Because a wireless phone is mobile, the MSC serving the wireless phone will change as the wireless phone moves to a coverage area of another MSC. This second MSC may be served by another PSAP. Thus, emergency calls from a wireless phone can end up being routed to and recorded at more than one PSAP.
For example, if, after initiating a first emergency call and the call being subsequently recorded at a SS-ECR and a PSAP-ECR, the call is dropped. The wireless phone initiates a second emergency call. However, between the time the first call was dropped and the second call initiated, the wireless phone may have moved to a location being served by another MSC. When the second emergency call is received by this second MSC, the second MSC causes the second call to be recorded at its associated SS-ECR and at the PSAP-ECR associated with the PSAP serving the second MSC. However, if the first and second MSCs are served by different PSAPs, the second emergency call will be recorded at a second PSAP-ECR. In such a situation, the first and second PSAP-ECRs will not have a record of the second and first emergency calls, respectively, to use in identifying fraudulent calls from that wireless phone.
If the first and second MSCs are served by the same PSAP, the second emergency call will be recorded at the same PSAP-ECR where the record of the two emergency calls may be used in identifying fraudulent calls from that wireless phone. However, when the PSAP-ECR identifies the wireless phone as a source of fraudulent calls, no other PSAP-ECR will have any indication that this identification. Thus, if the wireless phone moves to a coverage area of a MSC being served by another PSAP, such PSAP would not know that the wireless phone has been identified as a source of fraudulent calls by another PSAP.
Accordingly, there exists a need to communicate records of emergency calls originating from wireless phones among multiple ECRs in order to better perform prevent fraud, and to communicate the identities of wireless phones which are the source of fraudulent emergency calls among multiple ECRs.